Furnace control



Apt. 3, 1923. 1,450,693

. E. MCLEAN FURNACE CONTROL Filed Oct. 21, 1920 I fishets-sheet 1 6f -T zv 7 WITNESS: INVEN TOR.

7 2 ATTONEYJ Apr. 3, 1923. 1,450,693

5. MCLEAN FURNACE CONTROL Filed 00b. 21, 1920 S sheets-sheet,

INVVLNTOR.

EMB'URY MCLEAN, GI BROOKLYN, NEW YORK.

FURNACE CONTROL.

Application filed October 21,1920. Serial No. 418,594.

To all whom it may concern:

Be it known that I, EMBURY MoLnAN, a

citizen of the United States, and resident of New York, borough ,of Brooklyn, in the county of Kings and State 'of New York, have invented certain new and useful Inn provements in Furnace Controls, of which the following is a specification,'

My invention relates-t6 new and useful improvements in control means for furnaces,

and particularly contemplates the provision of improved means for controlling a plurality of operating or regulating devices for furnaces, whereby the same will be caused to function synchronously, or in de sired or proper relation to each other.

The invention consists in the improvements to be more fully described hereinafter, and the novelty of which will be particularly pointed out and distinctly claimed.

Ihave fully and clearly illustrateda preferred embodiment of my invention in the accompan in drawin s to-be taken as a y g g part of this specification, andwherein- Figure 1 is a'view in side elevation showin a furnace having my improvements applied thereto. g

Fig. 2 is an enlarged view, partly in section, of the various elements detached from the furnace, but arranged so. as to clearly show the function and operation of said parts, and

Fig. 3 is a view in part diagrammatic, and in section showing the same invention applied to the control of electric regulating or operating means'fora furnace.

Referring to the drawings/by characters of reference, A designates generally a furnace structure, the same for the purpose of this application being shown generally as a steam boiler furnace, and showing one side wall 1. a front wall 2 and rear wall 3, the fire-pit or combustionchamberbeing shown at 4, an? an upp ef steam drum at 6. The furnace; s provided at its upper rear portion with astack or outletflue 7 The parts just described specifically form no part of my inventionland are shown merely for purposes of exeinplification', in order that the applica tion and operation of my invention, to be described hereinafter, will be fully understood. It will be understood by those skilled in the art, that the invention may be applied to other types of furnaces without departing in any way from the invention.

In the present embodiment, the invention is shown as functioning to control the relative operation of draft-controlling means and fuel-feeding means in a furnace pro vided with means such as shown in my Patent No. 1,071,771, dated September 2, 1913, for maintaining a constant pressure in the fire chamber of the furnace for varying rates of combustion, but I desire it understood that my invention is not limited to this combination of apparatus.

In this embodiment shown, the outlet 7 from the furnace is connected to the inlet of an exhaust apparatus, preferably a suitable fan 8, the outlet of which delivers the exhaust gases and products of combustion to the main stack or chimney, not shown. This exhaust apparatus may be driven by a suitable motor, shown in the form of a steam engine 9, having suitable pipe connections 10 to a source of steam pressure, and containing a throttle valve 11 operable by a lever 12 fulcrumed at 13 on the casing of the said valve.' By swinging movement of the lever in the manner hereinafter described, the throttle valve is operated to increase or decrease the supply of steam to the engine to thereby regulate-the speed of the fan, and consequently the draft from the furnace.

The fire-box or chamber of the furnace is provided with any suitable means for feeding fuel thereto, the same being shown in the form of a power driven stoker 14: for feeding coal or other fine fuel. The stoker is driven by a suitable motor, the same being shown in the form of a steam engine 15 geared to the said stoker by any suitable means, as for example sprocket wheels 16, 17, and drive chain 18. The engine is provided with a suitable steam inlet pipe 19 leading to a suitable source of steam pressure, said pipe containing a throttle valve 20 operated by a lever 21 fulcrumed on'the throttle valve casing as at 22. By swinging the lever 21 up or down, the throttle valve opening is closed or opened to reduce or increase the. supply of steam to the engine,

vention contemplates improved means for operating said controlling means, whereby the exhaust fan and the stoker will function to maintain proper conditions within the furnace, a preferred embodiment of which means I will now describe: M

In one of the walls of the furnace, preferably the side wall, is provided an opening 23, in which is arranged or fulcrumed a swinging plate 24, the opposite faces of which are exposed to the pressures existing respectively within the furnace chamber, and the atmospheric pressure external thereto. This construction and arrangement is preferably that shown and described in my said LettersPatent No. 1,071,771, and need not be further described specifically. As described in said patent, the plate is preferably provided with a counterweight 25, so that the pivot of the plate passes substantially through the center of gravity of the plate. Connected to the plate is a valve rod 26, extending within the casing 27 of a pilot valve, which rod carries a valve body 28 cooperating with an inlet 29 and an outlet 30 in such manner that, when the plate swings inwards, due to external excess pressure, said valve will shut off communication between the inlet-and the outlet and open communication between the outlet and a vent pipe 31, whereas, when the plate swings outwards under excess of internal pressure, the valve 28 will be moved downwards to cut 03 com-' munication between the outlet and the vent and establish communication between the inlet and the outlet. The inlet is connected by a pipe 32 with anysuitable source of fluid under pressure, while the outlet is connected with one end of a pipe 33, the other end of which communicates, as at 34, with one end of a cylinder 35, in which is ar-' passes through a suitable guide sleeve 41 on.

a bracket 42, and thence over a guide pulley 43 and about a reducing pulley 44, said chain being anchored to said pulley, in any suitable manner, as at 45. The pulley is mounted upon a shaft 46, which may be arranged in bearings of any suitable type, and upon any suitable support, not shown. The pulley 44 is provided with a smaller drum portion 47, upon which is wrapped one end of a flexible connection, preferably a chain 48, the opposite end of which is connected, as at 49, to the free end of the lever 12 for operating the throttle valve 11, heretofore described. The chain 48 may be provided with a turn-buckle 50, or other suitable means for tensioning the same properly and adjusting its length,

Also mounted upon the upper end of therod 38 is a collar 51, to which is connected one end of a tension spring'52, the other end of which is connected by a suitable collar 53 to the said sleeve 41, the latter being adjustably threaded in the bracket 42, whereby tension on the said spring may be adjusted. Also wrapped upon the drum 44 is a chain section 54 carrying a weight 55 which opcrates to rotate the drum 44 to unwind the chain 48, under conditions to be presently described.

Connected to the pipe 32, heretofore described, is one end of a pipe 56, the other end of which communicates with the cylinder 35 at a point between the piston 36 and the end of said cylinder from which the rod 38 projects, communication between said pipes 32 and 56 being free at all times so that the piston is subjected to the pressure existing in the said pipe 32, which pressure opposes the tension of the spring 52 and the force of gravity of the weight It will be seen that this constant pressure supplied through the pipes 32-and 56 normally tends to move the piston 36 downwards, and through the intermediate connections to raise the lever 12 to reduce the supply of fluid pressure to the fan engine, but is opposed by the spring 52 and weight 55, and pressure which under control of the pilot valve may be admitted to the lower end of the cylinder 35. The connections and arrangements are such that when the plate 24 is in its intermediate position with the pilot valve closed, the throttle valve functions to maintain a fixed opening and the fan engine runs at a constant speed, but when the plate swings inwards under a preponderance of external pressure, the pilot valve 28 cuts ofl communication between the pipes 32 and 33, and permits the pressure in the latter to escape through the vent pipe 31, the force exerted by the pressure on the upper face of the piston 36 being greater than the tensile strength of the spring 52- and the force exerted by the weight 55. The piston moves downwards and the drum 44. is then turned countercloclnvise, as shown inl ig. 2. to lift the lever 12 and reduce the flow of steam through the throttle valve 1.1, and thereby reduce the speed of the engine 9 and fan 8. As soon as the reduction'of speed of the fan results in an increase of pressure within the furnace, the plate 24 moves outwards, thereby moving the pilot valve into position to establish communication between the pipe 32 and the pipe 33, and cut off the latter from the vent 31, whereupon the fluid pres sure is exerted upon-the lower face of the piston 36 and acts in the same direction as the force of the spring, which pressure. together with the tension of the spring 52 and force of the weight overcomes the pressure upon the upper face of the piston 36,

projecting through the head of the cylinder, as at 60, and connected as at 61 to one end of a chain 62 pasing through a sleeve 63 mounted on a bracket 64, 0 any suitable support, and fromwhich sleeve said chain is led over suitable guide pulleys 65, and thence to a connection with the lever 21 for operating the throttle valve to the stoker engine.

Also connected to the upper end of the rod 60 is a collar 66 to which is secured one end of a tension spring 67, the other endof which is-connected to a collar 68 carried by,

the said sleeve 63, the latterbeing threaded through the bracket 64, whereby the tension of the said spring-may be adjusted. The construction. of the two cylinders 35 and 57 is similar, and the size and strength of the springs 52 and 67 are preferably made as near the same as possible. Connecting the pipe 56 with the opposite end of the cylinder 57 from that to which the pipe 156 isconnected, is a pipe 69, by means of which fluid pressure is fed to the cylinder 57 from the pipe 32. By the pipe arrangement described, it'will be seen that when the plate 24: swings to control the fluid pressure in one cylinder, the same fluid pressure conditions will be maintainedin the other cylinder, so

that they may be made to operate in sub-.

stantial synchronism.

It will be apparent that if the chain 62 is connected directly to the lever 21 the two throttle valves will work in substantial synchronism, 'so as to always have corresponding positions. This, however, might not be the desired relation, and I therefore interpose a suitable connection whereby for any speed of the exhaust fan a desired corresponding speed of the stoker engine may be obtained This njteans consists of an adjustable ca; preferably cdnsisting of a rotatable disc 70 fixe'd to ashaft 71 mounted in suitable bearings, not shown, and having a hub 72 about which the chain-62 is wrapped in the direction whereby'a pull on the chain rotates the cam counterclockwise, and release ofthe chain permits the cam to be turned clockwise by the force of a weight 73 suspended from a chain 74.wrapped on;- ;the hub 72 in the opposite direction from the chain 62. The disc 70 is provided with a plurality of radial slots in which are arranged adjustable abutments in the form of bolts 75, which permit radial adjustment of said bolts in order to provide the desired cam surface necessary to give the desired swinging movement of the lever 21 to operate the throttle yalve 20 to give the desired control of fluid pressure to the engine 15. This adjustable cam is preferably of the construction shown in my prior Patent Number 1,355,157, and

which need not be more specifically described herein, as the same does not specifically constitute the invention of this application.

It will be seen that by the arrangement 'shownand described, the plurality of oper ating cylinders are causedto act in substantlal synchronism to control separate operating or regulating means associated with the furnace, and that the motion or force ap plied by one of said cylinders may be so regulated or adjusted as to cause the means operated thereby to bear any desired relation to the means operated by another of said cylinders. Ordinarily, however, it is desirable tooperate the pistons of the two. pressure cylinders in synchronism. Because of variation in friction of the pistons in the cylinder, variations in leakage past the pistons and variations in other factors, it is impossible so to construct the pressure cylinders and associated parts that they will operate and continue to operate in synchronism, when subjected to the same pressure. In accordance with applicants invention means comprising adjustable springs associated with the respective'pressure cylinders are provided which cause the pistons to operate, in synchronism.-

, It will also be seen that by the arrange; ment shown'and described I am able to synchronously 'control the operation or function of different elements of a furnace which may be widely separated, without the inter-- position of chains and pulleys, or other mechanical connections.

In Fig. 3 I have shown a modified form of the invention as applied to the control of an electric motor constituting the driving means for the stoker in place of a steam engine. ,In this form of the invention, the counterpart of the cylinder 57, heretofore described, is shown at 57 the latter through the piston 58, piston rod 59*, piston rod extension 60*, flexible connection 62 operating a. camvmember 70, all constructed and operated by fluid pressure admitted and exhausted from the saidregulator pipes 78, 79. The piston of this regulator is connected by a link 80 and bell-crank 81 to a flexible connection 82 operating a quadrant-operating device 83 connected to a controlling arm 84; of an electric controller or rheostat 86, 87 to a suitable motor, not shown, for driving the motor. It will be understood that the cylinder 57 is operated and controlled in the same manner as the cylinder 57, heretofore described, and synchronizing with a cylinder similar to the cylinder ing each controller and connected to a common source of pressure, a valve controlling said pressure, and means comprising adjustable springs acting in the same direction as said pressure-operated means for synchronizing the operation of said pressure-operated means.

3. In combination, a. furnace, a plurality of independent operating means for the furnace, a controller for each of said means, apressure cylinder for operating each controller and connected to a common source of pressure, and means ci'imprising adjustable sprin s for synchronizing the operation of said cyfinders.

4. In combination, a furnace, draft-regulating means for the furnace, a controller for the draft-regulating means, fuel-feeding means, a controller for the fuel-feeding means, pressure cylinders for operating said controllers and connected to a common source of pressure, and means for synchro: nizing the operation of said cylinders.

5. In combination, afurnace, draft regulating means for the furnace, a controller for the draft-regulating means, fuel-feeding means, a controller for the fuel-feeding means, pressure cylinders for operating said controllers and connected to a common source of pressure, and means comprising adjustable springs for synchronizing the operation of'said cylinders.

6. In combination, a furnace, draft means for the furnace, an engine for driving said draft means, a controller for said engine,

fuel-feeding means, an engine for driving said fuel-feedmg means, a controller for said last-named engine, pressure cylinders for 1,45c,ees

operatingsaid controllers and connected to a common source of pressure, and means for synchronizing the operation of said cylinders.

7. In combination, a furnace, means movable in accordance with variations in pressure in the furnace chamber, a plurality of independent operating means for the furnace, a controller for each of said means, a pressure cylinder for operating each controller and connected to a common source of pressure, means for synchronizing the operation of said cylinders, and means whereby the pressures ofsaid cylinders is controlled by said first-named means.

8. In combination, a furnace, means movable in accordance with variations in pressure in the furnace chamber, a plurality of independent operating means for the furnace, a controller for each of said means, a

pressure cylinder for operating each controller and connected to a common source of pressure, means comprising adjustable springs for synchronizin the operation of said cylinders, and means whereby the pressures of said cylinders is controlled by said first-named means. r

9. In combination, a furnace, means movable in accordance with variations in pressure in the furnace chamber, a plurality of independent operating means for the furnace, a controller for each of said means, pressure-operated means for operating each controller and connected to a common source of pressure, a valve for controlling said pressure and operable by said first-named means, and means comprising adjustable springs for synchronizing the operation of said pressureoperated means and acting in the same direction as said. spring means for s \'nchroniz ing the operation of said pressure-operated means.

10. In combination, a furnace. a plurality of regulating devices therefor, and means for controlling the operation of said devices comprising a fluid pressure operated device associated with each of said regulating devices, the two fluid pressure operated devices being connected to a common source of fluid pressure, and means associated with the respective regulating devices for causing them to operate in synchronism.

In testimony whereof I have hereunto signed my name in the presence of 'the subscribing Witness.

. IMBURY McLEAN. Witness:

AoNns E. CUNNEEN. 

